The present invention relates to a method and system for the removal of hair from animals prior to slaughtering of such animal, and to reuse, recycling and disposal systems for compositions generated in such a dehairing method.
In the meat industry, and particularly in those areas devoted to the processing of beef and pork, meat packers slaughter animals in a process in which the animals are stunned, bled, skinned, eviscerated, and fabricated into meat sections which are marketable to the public or the restaurant trade. Animals enter a meat slaughter plant with various foreign materials present on their hair, including blood, dirt, manure, mud and vegetative material. An animal""s hair is also contaminated with a multitude of microorganisms, some of which are pathogenic to humans. Most bacteria present in a meat slaughter and processing facility are carried into the facility on the hides of animals to be slaughtered. During the slaughtering process, these microorganisms contact meat and other meat by-products, thereby contaminating such products, creating handling problems and reducing the shelf life and safety of meat products.
The control of contamination by microorganisms is a recognized problem in the meat packing industry. Many techniques have been employed in the past in an effort to destroy surface bacterial flora on meat. For example, U.S. Pat. No. 4,852,216 to Clayton discloses a disinfection system using acetic acid spray in order to reduce bacteria levels and thereby increase shelf life of meat products. Other inventors have utilized anti-microbial agents for preserving products normally subject to microbial spoilage. For example, U.S. Pat. No. 3,915,889 to Jurd discloses a certain anti-microbial agent that can be applied for preservation of a wide variety of substances including meat by-products.
Still other inventors have recognized the advantages of dehairing animals to facilitate the slaughtering process. U.S. Pat. No. 4,674,152 to Georges discloses an apparatus and method for slaughtering animals by bleeding an animal, electrostatically charging the animal""s hair, applying a combustible fluid to the hair and subsequently igniting the combustible fluid to burn the hair from the animal""s body. U.S. Pat. No. 4,309,795 to Simonsen discloses a method and apparatus for dehairing hogs wherein the hog is bled, its skin is scalded with hot water and then subjected to abrasive treatment to remove the hog""s hair. U.S. Pat. No. 5,149,295 to Bowling et al., which is incorporated herein by reference in its entirety, discloses the use of a depilatory substance to remove animal hair, such depilatory substance including a chemical that is able to cleave disulfide bonds between cysteine amino acid residues present in animal hair.
Methods for dehairing which use chemicals to remove animal hair, however, generate chemical and animal byproducts which can be toxic and/or environmentally hazardous and can pose significant problems for waste disposal. Therefore, a need exists for a method for dehairing animals which includes protocols for recycling and/or safely disposing of compositions and waste products produced during the process. The present invention addresses such a need by providing a process for reducing bacterial contamination of meat and meat by-products from the outset of the slaughtering process, prior to the exsanguination of the animal, while minimizing the cost and environmental impact of such a process through a novel recycle, reuse and disposal system.
The present invention is directed to a method and system for dehairing animals which includes processes for recycling, reusing and safely disposing of chemical and biological waste products from such a dehairing process. More particularly, the present invention is generally directed to a process for dehairing an animal, which includes the steps of immobilizing the animal, prewetting the hide, applying a depilatory substance to the hide, removing the hair from the hide, and dispatching the animal. In certain embodiments, the present method also includes the steps of neutralizing the hide and washing the hide with fresh water. Included in each step of this method are collection, recycling and waste disposal processes for treating individual or combined waste streams from the prewetting, depilatory application, hair removal, neutralizing (if necessary) and fresh water rinse (if necessary) steps. As used herein, xe2x80x9cliquid and/or solid wastesxe2x80x9d are meant to include liquid and/or solid constituents since such liquids and/or solids may be recyclable and thus may not be technically deemed to be xe2x80x9cwastesxe2x80x9d.
Such processes for waste stream treatment can include the steps of: (a) separation of solid waste from liquid waste; (b) further separation, recycling and disposal of solid wastes; and (c) treatment and recycling of liquid wastes. Step (b) of further separation, recycling and disposal of solid wastes can include separation of hair from other solids such as mud and manure, followed by recovery of valuable proteins from the hair and recycling/disposal of mud and manure to land applications or landfills. Step (c) of treatment of the liquid waste can include any or all of the steps of (a) removing fine solid waste from the liquid; (b) recovering and recycling water from the liquid waste; (c) recovering and recycling sulfides from the liquid waste; (d) controlling, removing and/or recycling of H2S gas from the liquid waste; and (e) recycle and/or disposal of residual sulfides in the liquid waste as sulfates.